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Is Your O2 amplifier The Real McCoy

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#2
Well, even JDS Labs had to modify the O2. In that the original power jack was no longer being made, so they had to use a different one. Does sound like Massdrop seriously changed some stuff they didn't HAVE to though.
 
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#3
I wonder if massdrop ever addressed the issue. It is too bad they are not building to spec if true. IIRC JDS Labs builds to spec and drilled out a few of the holes on the pcb so the alternate power jack fits.

Years ago, I did my share of modding the O2. I built one with +/- 15v rails to handle higher gain. Also added heat sinks to the IC's and voltage regulators. Even exchanged a few messages with nwavguy at one point. AGDR on diyaudio.com went a bit further and built booster boards and his own version of the "desktop" O2.
 

Wombat

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#4
I wonder if massdrop ever addressed the issue. It is too bad they are not building to spec if true. IIRC JDS Labs builds to spec and drilled out a few of the holes on the pcb so the alternate power jack fits.

Years ago, I did my share of modding the O2. I built one with +/- 15v rails to handle higher gain. Also added heat sinks to the IC's and voltage regulators. Even exchanged a few messages with nwavguy at one point. AGDR on diyaudio.com went a bit further and built booster boards and his own version of the "desktop" O2.
If Amirm can get both an older one(e.g. Mayflower) and a newer one(JD Labs) to test we could see if it is worth fussing about from a performance point of view. ;)
 
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#5
If Amirm can get both an older one(e.g. Mayflower) and a newer one(JD Labs) to test we could see if it is worth fussing about from a performance point of view. ;)
Or an older JDS Labs one... since Mayflower used parts from JDS at their start. I don't think that's really even required that much though. Just a newer one to compare against BoM to see if it's still the same outside the power jack.
 

Timbo2

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#6
Well, even JDS Labs had to modify the O2. In that the original power jack was no longer being made, so they had to use a different one. Does sound like Massdrop seriously changed some stuff they didn't HAVE to though.
I seem to remember reading you had two choices - trim the leads on the replacement power jack to make it fit or enlarge the holes on the board. I believe that JDS made a board revision with slightly larger holes.

I ordered a JDS Labs O2 with the rear power jack. For that modification they solder two wires to the jack location on the front of the board and run them across the top of the board and out to a jack mounted in the back.

Modifications like that or changing the output jack size don't concern me. Making changes to the design when the electronic component parts still exist and are readily obtainable would concern me too.

But even JDS is taking a few liberties with the design. In my example they mounted some components on the bottom of the board that should be on the top of the reference design. It would appear they do this to make it easier to add inputs and outputs on the rear panel.
 

amirm

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#7
I recently evaluated a Grace Design DAC+O2 amp. It was a huge mess inside courtesy of the strict licensing rules. So personally I am not sympathetic to the cause. NWAVGUY should have put the thing in public domain without such restrictions to allow more innovation. The world is advancing and keeping a good design stuck in the mud is not good.
 

Timbo2

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#8
I recently evaluated a Grace Design DAC+O2 amp. It was a huge mess inside courtesy of the strict licensing rules. So personally I am not sympathetic to the cause. NWAVGUY should have put the thing in public domain without such restrictions to allow more innovation. The world is advancing and keeping a good design stuck in the mud is not good.
I'm torn.

I understand why he did what he did, but as you point out it makes for messy design when folks add features and it stifles innovation.
 

Wombat

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#9
Unless NwAvGuy resurfaces with objections re license issues the matter is just an item of limited interest.
 

mindbomb

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#10
I have a massdrop o2, the desktop edition. I haven't opened mine up, but I have seen other people that did it. The power, the rca input, and headphone jack is attached to the pcb by cables, which is pretty ridiculous. This is all because they couldn't modify the board.

Though my led and volume pot seem like they are the what they were supposed to be. There didn't appear to be substitutions there.
 
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#11
I have a massdrop o2, the desktop edition. I haven't opened mine up, but I have seen other people that did it. The power, the rca input, and headphone jack is attached to the pcb by cables, which is pretty ridiculous.
Without modifying the design, to get rear RCA-inputs, a 1/4" jack, and rear power, you kind of have to use wires to connect. It would be NICE if they could adjust the PCB, but that would be a serious modification to the design of the amp.
 
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#12
I have a massdrop o2, the desktop edition. I haven't opened mine up, but I have seen other people that did it. The power, the rca input, and headphone jack is attached to the pcb by cables, which is pretty ridiculous. This is all because they couldn't modify the board.

Though my led and volume pot seem like they are the what they were supposed to be. There didn't appear to be substitutions there.
The board is designed for use of off-board inputs and outputs. It's in the circuit schematics and there are pads on the board as well, P1 and P2.
 
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#13
I recently evaluated a Grace Design DAC+O2 amp. It was a huge mess inside courtesy of the strict licensing rules. So personally I am not sympathetic to the cause. NWAVGUY should have put the thing in public domain without such restrictions to allow more innovation. The world is advancing and keeping a good design stuck in the mud is not good.
His licensing doesn't allow for derivative works, which is understandable given what happened with the Cmoy amp and the numerous ****** clones.

That said, the amplifier design is nothing special. It's an opamp in a gain stage connected by the volume pot to two opamps as an output buffer. Maybe half of the components on the board are spent on the power regulation. His greatest contribution in the design was choosing and measuring components to come up with a BOM that is performant at a set price.

It wouldn't be terribly hard to build a similar amp that doesn't infringe on the licensing, but there's not much point to aside from a hobbiest project. I'm thinking of cobbling one together on a breadboard using a LPS (or SMPS with filtering) instead of the AC input.
 
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#14
it's an opamp in a gain stage connected by the volume pot to two opamps as an output buffer.
Aren't they all, more or less?
Some more , some less?

His greatest contribution in the design was choosing and measuring components to come up with a BOM that is performant at a set price.
Isn't this what everyone before the O2 and after the O2 still trying to achieve?
"Everybody" , their brother, at least two uncles and distant cousin is producing yet another headphone amp.

As for the gripe fof having to connect RCA with wires instead of modifying the board to avoid two inches (or less ) of wire, I mean c'mon....two extra inches to another foot or two of interconnect just 'aint gonna make a difference, (other than creating gripe threads) :)
 
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#15
Isn't this what everyone before the O2 and after the O2 still trying to achieve?
"Everybody" , their brother, at least two uncles and distant cousin is producing yet another headphone amp.
True, and I don't mean to discount the effort. The O2 has measurements to back up its claims, which is not true of most of the hobbyist (or commercial) products.

I think the cMoy amp was the first really popular DIY headphone amp available, and it's honestly a bit garbage.

As for the gripe fof having to connect RCA with wires instead of modifying the board to avoid two inches (or less ) of wire, I mean c'mon....two extra inches to another foot or two of interconnect just 'aint gonna make a difference, (other than creating gripe threads) :)
But be sure to use super-special audio grade wire...
 

trl

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#16
I paid about 60 USD on my O2 few years ago, when it was "in vogue"; it was a DIY kit and it worked perfectly from the first run.

Some measurements could be found here: https://www.neurochrome.com/o2-headphone-amp/#Measurements.

It is indeed super silent when 1X gain is used, so no problems running sensitive IEMs. Of course, it will drive most cans out there, but the new JDS Atom beats O2 on most technical aspects.
 

solderdude

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#17

Timbo2

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#18
Grado made a lot of money on their C'Moy (RA-1) for $ 400.-
Oh my... I especially like how they couldn't be bothered to route out for the cable that goes over the potted component.

Edit - I take that back there is a small channel there.
 

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